[RE-wrenches] NEC 480 - battery enclosure question
Kent Osterberg
kent at coveoregon.com
Wed Dec 14 22:15:55 PST 2011
Dan,
While the battery box, or maybe the whole room they are in, do fit the
definition of a Class 1 Division 2 location, I don't think it is
consistent with the intent of that section. Wring methods for hazardous
locations are specifically designed to keep the wiring isolated from the
hazard. That notion doesn't work batteries - they are the source of the
hazard and the wires do run to, and into, them. To be complaint with the
requirements for hazardous locations the batteries would have to have
integrated gas tight junction boxes enclosing the terminals. And
interior of the battery would still remain an explosive environment with
energized conductors no matter what is done to wiring on the exterior of
the battery. Batteries are a special hazard and wiring methods specified
for Class 1 Division 2 locations won't mitigate that hazard.
It takes a lot of ventilation to keep the H2 levels below the explosive
threshold.
Kent Osterberg
Blue Mountain Solar, Inc.
www.bluemountainsolar.com
t: 541-568-4882
On 12/14/2011 4:46 PM, dan at foxfire-energy.com wrote:
> I've mentioned it in the past, and got the impression it went over
> like a fart in church, but it seems to me buttoning up a battery box
> tighter than a bull's ass in fly season, and (hoping) mechanical
> ventilation mitigates this creation of a hazardous environment creates
> a Class I, Division 2 location. (NEC 500.5 (B)(2)(2)).
> Any takers?
> db
>
>
> Dan Brown
> Foxfire Energy Corp.
> Renewable Energy Systems
> (802)-483-2564
> www.Foxfire-Energy.com <http://www.Foxfire-Energy.com>
> NABCEP #092907-44
>
>
> -------- Original Message --------
> Subject: Re: [RE-wrenches] NEC 480 - battery enclosure question
> From: Ray Walters <ray at solarray.com <mailto:ray at solarray.com>>
> Date: Wed, December 14, 2011 11:52 am
> To: RE-wrenches <re-wrenches at lists.re-wrenches.org
> <mailto:re-wrenches at lists.re-wrenches.org>>
>
> 110.11 Deteriorating Agents. Unless identified for use in
> the operating environment,no conductors or equipment
> shall be located in damp or wet locations; where exposed to
> gases, fumes,vapors, liquids, or other agents that have a
> deteriorating effect on the conductors or equipment; or
> where exposed to excessive temperatures.
> Informational Note No. 1: See 300.6 for protection against
> corrosion.
>
> 110.18 Arcing Parts. Parts of electrical equipment that in
> ordinary operation produce arcs, sparks, flames, or molten
> metal shall be enclosed or separated and isolated from all
> combustible material.
>
> 300.6 Has a lot of good info on corrosion that we in the solar biz
> should be all over, as well.
>
> So that's 3 pretty specific code references.
>
> Ray Walters
>
> On 12/13/2011 7:03 PM, boB at midnitesolar.com wrote:
>> On 12/13/2011 5:47 PM, Dan Fink wrote:
>>> Esteemed Wrenches;
>>> An email question from my recent Home Power article on charge
>>> controllers that I'm unsure of.
>>> Does NEC specifically forbid mounting other gear, such as charge
>>> controllers, inside a battery enclosure? How about shunts?
>>> It's not in 480 that I can see, and 480 doesn't seem to treat
>>> the interior of a battery enclosure as particularly explosive,
>>> because as per 480 it has to be adequately vented anyway.
>>> Of course there are a zillion common-sense reasons not to
>>> actually DO that -- even an MX60 has a relay that can spark--
>>> and of course corrosion on the controller terminals, circuit
>>> board, etc. Bad news all around and I never do it. I learned
>>> this as an apprentice back in the 1990s, and I just don't do it.
>>> But I do put shunts in there sometimes...is this a no-no? The
>>> shunt terminals are brass, I've never seen any really nasty
>>> corrosion build up, but I'm quite curious.
>>> BUT I'm wondering if I'm missing something obvious in some
>>> other NEC section etc.
>>>
>>> Thanks in advance!
>>>
>>
>>
>> Hi Dan. Nice article, BTW !
>>
>>
>> The NEC doesn't say that you CAN do this, but it does not
>> dis-allow it either.
>>
>> It will come down to what the battery manufacturer says, is what
>> we have found.
>>
>> Sealed batteries are the only ones that can be mounted in a
>> battery box with
>> arc and spark equipment.
>>
>> Look at UPS's that you buy from COSTCO for instance. They are UL
>> listed, usually.
>>
>> boB
>>
>>
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